(Trichloromethyl)pyridine compounds, such as nitrapyrin, have been used as nitrification inhibitors in combination with fertilizers as described in U.S. Pat. No. 3,135,594, which is herein incorporated by reference. These compounds maintain applied ammonium nitrogen in the ammonium form (stabilized nitrogen), which enhances crop performance. It would be desirable to broadly apply these compounds with nitrogenous fertilizer at sowing time, but due to potential volatility losses, these application methods are generally unsatisfactory. In addition nitrapyrin has been added to anhydrous ammonia, which by default must be injected into the soil.
Other nitrapyrin formulations have been applied to the surface of the soil, but must either be incorporated mechanically, or watered into the soil within 8 hours after application to overcome volatility losses. Finally, rapid or dump release capsule formulations of nitrapyrin encapsulated with lignin sulfonates have also been disclosed in U.S. Pat. No. 4,746,513, which is incorporated herein by reference. However, although the release of nitrapyrin is delayed by the encapsulation, the capsules release all of the nitrapyrin upon contact with moisture, exhibiting the same stability and volatility disadvantages of the prior application methods. Additionally, these formulations are difficult and costly to produce and cannot be used with liquid urea ammonium nitrate (“UAN”) fertilizers.
Polycondensation encapsulation, as disclosed in U.S. Pat. No. 5,925,464, has been used to encapsulate agriculturally active ingredients, particularly to enhance handling safety and storage stability of the active ingredient by using polyurethane rather than polyurea encapsulants.
However, there remains a need to deliver nitrification inhibitors such as (trichloromethyl)pyridines, that exhibit greater long term stability in the field environment, while maintaining levels of efficacy comparable to that of un-encapsulated nitrification inhibitor formulations.
A first set of embodiments including a microcapsule suspension formulation, comprising: (a) a suspended phase, the suspended phase including a plurality of microcapsules, the microcapsules having a volume median particle size of from about 1 to about 10 microns, wherein the microcapsules comprise: (1) a microcapsule wall produced by an interfacial polycondensation reaction between a polymeric isocyanate and a polyamine to form a polyurea shell having a weight percentage of about 0.2 to about 40 percent of a total weight of the microcapsule suspension formulation, and (2) a substantially liquid core, the substantially liquid core is encapsulated within the polyurea shell, wherein the substantially liquid core includes no more than about 60 weight percent of a nitrification inhibitor, some of these embodiments, the nitrification inhibitor is 2-chloro-6-(trichloromethyl)pyridine, and the substantially liquid core in these embodiments includes no more than 1.0 weight percent of solid 2-chloro-6-(trichloromethyl)pyridine, as determined at a temperature greater than or equal to 15° C.; and (b) an aqueous phase, wherein the aqueous phase includes at least about 1.0 weight percent aromatic solvent, in some preferred embodiments the aromatic solvent in the aqueous phase is added after formation of the microcapsules.
A second set of embodiments including a microcapsule suspension formulation according to the first set of embodiments and, further including: at least one ionic stabilizer present in the aqueous phase.
A third set of embodiments including a microcapsule suspension formulation according to the first or second set of embodiments, wherein the aromatic solvent present in the aqueous phase is at least one compound selected from the group consisting of: light aromatics, naphthalene depleted light aromatics, heavy aromatics, and naphthalene depleted heavy aromatics.
A fourth set of embodiments including a microcapsule suspension formulation according to the third set of embodiments, wherein the aromatic solvent present in the aqueous phase is naphthalene depleted heavy C10-13 aromatics.
A fifth set of embodiments including a microcapsule suspension formulation according to the fourth set of embodiments wherein the aromatic solvent present in the aqueous phase comprises between about 1% by weight and about 10% by weight naphthalene depleted heavy C10-13 aromatics.
A sixth set of embodiments including a microcapsule suspension formulation according to the fourth set of embodiments wherein the aromatic solvent present in the aqueous phase, comprises between about 2% by weight and about 5% by weight naphthalene depleted heavy C10-13 aromatics.
A seventh set of embodiment including a microcapsule formulation according to the fourth set of embodiments, wherein the aromatic solvent present in the aqueous phase comprises between about 2.5% by weight and about 3.0% by weight naphthalene depleted heavy C10-13 aromatics.
An eighth set of embodiments including a microcapsule suspension formulation according to the third set of embodiments wherein the aromatic solvent present in the aqueous phase is heavy C10-13 aromatics.
A ninth set of embodiments including a microcapsule suspension formulation according to the eighth set of embodiments wherein the aromatic solvent present in the aqueous phase comprises between about 1% by weight and about 10% by weight heavy C10-13 aromatics.
A tenth set of embodiments including a microcapsule suspension formulation according to the eighth set of embodiments, wherein the aromatic solvent present in the aqueous phase comprises between about 2% by weight and about 5% by weight heavy C10-13 aromatics.
An eleventh set of embodiments including a microcapsule suspension formulation according to the eighth set of embodiments, wherein the aromatic solvent present in the aqueous phase comprises between about 2.5% by weight and about 3.0% by weight heavy C10-13 aromatics.
A twelfth set of embodiments including a microcapsule suspension formulation according to the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenths, or eleventh sets of embodiments wherein the microcapsules have a volume median particle size of from about 1 to about 5 microns.
A thirteenth set of embodiments including a microcapsule suspension formulation according to the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenths, eleventh, or twelfth sets of embodiments, wherein the ratio of the suspended phase a) to the aqueous phase b) is from about 1:0.75 to about 1:100.
A fourteenth set of embodiments including a microcapsule suspension formulation according to the thirteenth set of embodiments wherein the ratio of the suspended phase a) to the aqueous phase b) is from about 1:1 to about 1:7.
A fifteenth set of embodiments including a microcapsule suspension formulation according to the thirteenth set of embodiments wherein the ratio of the suspended phase a) to the aqueous phase b) is from about 1:1 to about 1:4.
A sixteenth set of embodiments including a microcapsule suspension formulation according to the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenths, eleventh, twelfth, thirteenth, fourteenth, or fifteenths sets of embodiments wherein the polymeric isocyanate is polymethylene polyphenylisocyanate.
A seventeenth set of embodiments including a microcapsule suspension formulation according to the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenths, eleventh, twelfth, thirteenth, fourteenth, fifteenths, or sixteenth embodiments further including a nitrogen fertilizer.
An eighteenth set of embodiments according the seventeenth embodiment wherein the nitrogen fertilizer is urea ammonium nitrate.
A nineteenth set of embodiments comprising the methods of suppressing the nitrification of ammonium nitrogen in a plant growth medium comprising the step of applying the microcapsule suspension formulations of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenths, eleventh, twelfth, thirteenth, fourteenth, fifteenths, sixteenth, seventeenth, eighteenth, and nineteenth embodiments to a plant growth medium.
A twentieth set of embodiments according to the nineteenth set of embodiments wherein the formulations are incorporated into the growth medium.
A twenty first set of embodiments according to the twentieth set of embodiments wherein the formulations are applied to a plant growth medium surface.
A twenty second set of embodiments a method for inhibiting nitrification, wherein the formulation according to the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenths, eleventh, twelfth, thirteenth, fourteenth, fifteenths, or sixteenth is applied in combination with a pesticide or sequentially with a pesticide.
A twenty third set of embodiments including the method according wherein the twenty second set of embodiments wherein the formulations are applied along with a nitrogen fertilizer.
A twenty forth set of embodiments according the twenty third set of embodiments, wherein the nitrogen fertilizer is urea ammonium nitrate. A microcapsule suspension formulation, comprising: a suspended phase, the suspended phase including a plurality of microcapsules, the microcapsules having a volume median particle size of from about 1 to about 10 microns, wherein the microcapsules comprise: (1) a microcapsule wall produced by an interfacial polycondensation reaction between a polymeric isocyanate and a polyamine to form a polyurea shell having a weight percentage of about 0.2 to about 40 percent of a total weight of the microcapsule suspension formulation, and (2) a substantially liquid core, the substantially liquid core is encapsulated within the polyurea shell, wherein the substantially liquid core includes no more than 40 weight percent 2-chloro-6-(trichloromethyl)pyridine of the entire microcapsule; and (b) an aqueous phase, wherein the aqueous phase includes at least about 1.0 weight percent aromatic solvent, wherein the at least 1.0 percent aromatic solvent is added to the aqueous phase after the formation of the microcapsules.
Further disclosed herein is a microcapsule suspension formulation comprising: a suspended phase of a plurality of microcapsules having a volume median particle size of from about 1 to about 10 microns, wherein a microcapsule comprises: a microcapsule wall produced by an interfacial polycondensation reaction between a polymeric isocyanate and a polyamine to form a polyurea shell having a weight percentage of about 0.2 to about 15 percent of a total weight of the microcapsule suspension formulation, and a compound encapsulated within the polyurea shell wherein said compound is 2-chloro-6-(trichloromethyl)pyridine; and an aqueous phase including an ionic stabilizer and dispersed aromatic solvent.
In some embodiments, the dispersed aromatic solvent is at least one compound selected from the group consisting of: light aromatics, naphthalene depleted light aromatics, heavy aromatics, and naphthalene depleted heavy aromatics. In other embodiments, the dispersed aromatic solvent is naphthalene depleted heavy C10-13 aromatics. Still in other embodiments, the formulation comprises between about 1% by weight and about 10% by weight naphthalene depleted heavy C10-13 aromatics. In yet other embodiments, the formulation comprises between about 2% by weight and about 5% by weight naphthalene depleted heavy C10-13 aromatics.
In some embodiments, the formulation comprises between about 2.5% by weight and about 3.0% by weight naphthalene depleted heavy C10-13 aromatics. In still other embodiments, the dispersed aromatic solvent is heavy C10-13 aromatics. Still in other embodiments, the formulation comprises between about 1% by weight and about 10% by weight heavy C10-13 aromatics.
Further, in exemplary embodiments, the formulation comprises between about 2% by weight and about 5% by weight heavy C10-13 aromatics. Alternatively, the formulation comprises between about 2.5% by weight and about 3.0% by weight heavy C10-13 aromatics.
In further embodiments, the microcapsules have a volume median particle size of from about 1 to about 5 microns. In other embodiments, the ratio of the suspended phase a) to the aqueous phase b) is from about 1:0.75 to about 1:100. Still in other embodiments, the suspended phase a) to the aqueous phase b) is from about 1:1 to about 1:7. In further embodiments, the ratio of the suspended phase a) to the aqueous phase b) is from about 1:1 to about 1:4.
Also disclosed is a microcapsule suspension wherein the polymeric isocyanate is polymethylene polyphenylisocyanate. In some embodiments, the polyamine is selected from ethylenediamine and diethylenetriamine.
Still further disclosed is a fertilizer composition comprising: a nitrogen fertilizer and the microcapsule suspension formulation described above. In other embodiments, the nitrogen fertilizer is urea ammonium nitrate.
Also disclosed herein is a method of suppressing the nitrification of ammonium nitrogen in growth medium comprising applying the microcapsule suspension formulation described above to said growth medium. In further embodiments, the formulation is incorporated into the growth medium. In still further embodiments, the formulation is applied to a growth medium surface. In other embodiments, the formulation is applied in combination with a pesticide or sequentially with a pesticide.
In still further embodiments, the formulation is applied with a nitrogen fertilizer. The nitrogen fertilizer can be urea ammonium nitrate.
The microcapsule suspension formulation of the present invention is stable and allows for delayed incorporation of nitrogen in crops, thus providing agronomic and environmental benefits. Surprisingly it has been discovered that a composition of microencapsulated (trichloromethyl)pyridine compounds, such as nitrapyrin, has superior performance when compared to unencapsulated compositions of nitrapyrin, even when incorporated into the soil.